Found in a 1947 publication, this circuit uses 4 parallel/push-pull tuber in the output stage. The circuit employs dual power supply with two rectifier tubes.
This simple experimental circuit using only transistor produces a tone given by C1 and C2. Tone is...
This power supply may have 5, 6, 9 or 12 V outputs depending on the 78XX and 79XX series...
This circuit is from Philips' 60s documentation. The circuit can be applied to modern operational...